To this date, there has been known a technique for presenting a suitable route to a destination to a vehicle driver, using a navigation device or the like. Moreover, there has been known a technique for presenting, for example, a route with a minimum required time, a route with a minimum traveling distance and a route with a minimum fuel consumption, as suitable route.
For instance, Patent Document 1 listed below discloses a technique regarding a fuel consumption information provision system which displays estimated fuel consumption information, i.e. information of predicted fuel amount consumed by traveling on a specific route searched by a navigation device. In this technique, in order to enhance the accuracy of the estimated fuel consumption information, actual fuel consumption information is collected at a central management device (center) from a plurality of vehicles, and based on the collected information, estimated fuel consumption information for each route is generated. The generated estimated fuel consumption information is provided to the navigation device and output. With this configuration, an option is presented to a vehicle driver to select a route with a fuel consumption expected to be the minimum.
In addition, Patent Document 2 listed below discloses a technique regarding a navigation device in which a route with a minimum fuel consumption is searched in accordance with a result of a fuel consumption simulation that uses various types of information, such as information of distance from a departure point to a destination, information of slope, information of load capacity, and congestion state of the road. Patent Document 3 listed below discloses a technique regarding a navigation system in which information associated with a fuel consumption or required time obtained by actual traveling of the vehicle are stored in a database, and based on this information, a route with a minimum fuel consumption, a route with a minimum required time and the like are searched.    Patent Document 1: JP2006-078326A    Patent Document 2: JP2000-002553A    Patent Document 3: JP02-278116A